1. Field of the Invention
The present invention generally relates to an apparatus and method for treating toxic or hazardous substances, such as NOx and SOx or the like, contained in exhaust or flue gases of, for example, a thermal (electric) power plant, a garbage burning facility (namely, a refuse incinerating facility), a toxic substance treating facility and a car by using a streamer discharge plasma. More particularly, the present invention relates to a streamer discharge plasma treatment apparatus and method for decomposing and detoxifying nitrogen oxides (hereunder described as NOx) and sulfur oxides (hereunder described as SOx) contained in exhaust or flue gases of a thermal power plant and so forth. Further, the present invention is applied to the decomposition and detoxification of VOC (namely, Volatile Organic Compound) gases generated in a chemical factory or the like. Furthermore, the present invention relates in general to a pulse generator for use in the aforementioned exhaust gas treating apparatus and method, and more particularly, to a pulse generator which is useful as a power supply in the case that electrodes are placed in gases such as exhaust gases discharged from a thermal power plant or the like, that a (streamer discharge) plasma is then generated by delivering pulse power (or energy) to these electrodes (namely, by applying a pulse voltage across the electrodes) and that toxic substances are treated through electrical action.
2. Description of the Related Art
Hitherto, for instance, what is called an ammonia catalytic reduction method has been employed for decomposing NOx. Further, what is called a lime-gypsum method has been employed for decomposing SOx. Thus, what is called chemical processing or treatment methods (or processes) have been principal techniques for removing NOx and SOx, which are contained in exhaust or flue gasses, therefrom.
Meanwhile, in recent years, a streamer discharge plasma exhaust gas treatment method has come to be employed as such a technique. In an apparatus for treating toxic substances contained in exhaust gases by using a streamer discharge plasma, the streamer discharge plasma is generated in a (plasma) reactor chamber. The configurations of, for example, a conventional line-pair cylindrical reactor chamber A and another conventional line-pair flat-plate-like reactor chamber B are illustrated in FIGS. 15 and 16, respectively. Streamer discharge plasmas are generated in the reactor chambers A and B by applying (same) high voltages V0 across a line electrode O1 and a cylindrical electrode O2 of FIG. 15 and across a line electrode O6 and a plate electrode O8 of FIG. 16, respectively.
Electrons originated (or drawn) from a streamer discharge plasma are accelerated by an electric field, so that these electrons become high-energy ones. The high-energy electrons contained in the streamer discharge plasma decompose and detoxify toxic substances, such as NOx and SOx, which are contained in exhaust gases, by colliding with the toxic substances. For instance, in the case of decomposing NO, such high-energy electrons collide with NO and N2 to thereby induce the following reaction: NO+Nxe2x86x92N2+O. Thus, NO is decomposed.
Radical density contributing to the decomposition of NO is determined by energy cast or applied to the streamer discharge plasma. Moreover, the reaction rate of a reaction component of a reaction system is also determined (incidentally, note that the treatment rate of NO is physically determined when the radical density is determined).
In the conventional method or system, one high-capacity high-voltage power supply and one high-capacity reactor chamber are used so as to generate a streamer discharge plasma. Incidentally, in FIGS. 15 and 16, reference characters O4, O5, O10 and O11 designate electric current introduction lines.
However, in the case of a reactor, which has one high-voltage power supply and one reactor chamber as illustrated in FIGS. 15 or 16, constant energy is cast into the entire reactor chamber, regardless of the concentration of the toxic substance. Thus, there is caused an excessive waste of energy in a region, in which the concentration of the toxic substance is low, in an outlet of the reactor chamber. Consequently, the energy required for the treatment is increased. Namely, when the concentration of the toxic substance is lowered to a target value in a reactor chamber, energy of the amount, which is not less than the necessary amount of energy, is consumed in the region in which the concentration thereof is low.
Further, as compared with the conventional chemical processing or treatment methods, the conventional streamer discharge plasma exhaust gas treatment method has large merit in that the facility therefor is in-expensive and that a space required to install the facility is small. The conventional streamer discharge plasma exhaust gas treatment method has large demerit in that the energy consumption required for generating a streamer discharge plasma is about 10 Wh/Nm3 and is thus a little under two times that (namely, about 6 Wh/Nm3) required in the case of the conventional chemical processing or treatment method.
Meanwhile, a pulse generator for generating large voltage pulses has been used as a power supply for use in an apparatus for performing the streamer discharge plasma exhaust gas treatment method.
FIG. 17 is a diagram conceptually illustrating the configuration of a conventional pulse generator of the distributed constant (or parameter) type that uses coaxial cables. In this figure, reference characters 1xe2x88x921 and 1xe2x88x922 denote distributed constant (or parameter) lines (namely, transmission lines); 3 a high-voltage side wiring line (or wire); 4 a low-voltage side wiring line; V0 a D.C. charger; S1 a shortcircuit switch; V1-1 and V1-2 voltages generated in the direction of arrows corresponding to the distributed constant lines 1xe2x88x921 and 1xe2x88x922, respectively; Z a load; and VP a voltage applied to the load Z.
The distributed constant lines 1xe2x88x921 and 1xe2x88x922 are coaxial cables, whose characteristic impedances are Z1a and Z1b, respectively, and whose lengths are L. Further, each of the distributed constant lines 1xe2x88x921 and 1xe2x88x922 is composed of: a corresponding one of cores (or core lines) 1xe2x88x921a and 1xe2x88x922a; and a corresponding one of outer conductors (made of shield braid or cladding materials or the like) 1xe2x88x921b and 1xe2x88x922b which surround the cores 1xe2x88x921a and 1xe2x88x922a through insulating materials (not shown), respectively. Incidentally, a folding-back point or portion is constituted only by the cores 1xe2x88x921a and 1xe2x88x922a that are not sheathed. These cores 1xe2x88x921a and 1xe2x88x922a are connected in series with each other. Further, an end (namely, an input-side portion) of these cores is connected to the D.C. charger V0 through the high-voltage side wiring line 3. On the other hand, the outer conductors 1xe2x88x921b and 1xe2x88x922b are connected to each other by a shortcircuit line 5xe2x88x921 at the side of the shortcircuit switch s1 (namely, at the input-side terminal or end portion) and is thus shortcircuited. Moreover, the input-side terminal portion of the outer conductor 1xe2x88x921b is connected to a grounding or earthing line serving as the low-voltage side wiring line 4. Furthermore, the input-side terminal portion of the outer conductor 1xe2x88x922b is connected to the high-voltage side wiring line 3 through the shortcircuit switch S1.
In this case, the impedance of the D.C. charger V0 acting as a power supply is matched to that of the load Z. Namely, Z=Z1a+Z1b.
Furthermore, in the case that the characteristic impedances of the distributed constant lines lxe2x88x921 and lxe2x88x922 are equal to each other, namely, in the case that the very same distributed constant lines lxe2x88x921 and lxe2x88x922 are used, the (voltage) propagation velocities of voltage signals in these distributed constant lines 1xe2x88x921 and 1xe2x88x922 are equal to each other. In the case where the dielectric constant of the insulating material is ∈ and the magnetic permeability thereof is xcexc, the voltage propagation velocity v is given by the following equation (1):                     V        =                  1                                    ε              ⁢                              xe2x80x83                            ⁢              μ                                                          (        1        )            
In the case of such a pulse generator, the shortcircuit switch S1 is opened as an initial condition. Further, the high-voltage side wiring line 3 indicated by a thick line is charged by means of the D.C. charger V0 to the voltage V0. In this case, an output voltage V 1xe2x88x921 of the distributed constant line 1xe2x88x921 is V0, while an output voltage 1xe2x88x922 of the distributed constant line 1xe2x88x922 is xe2x88x92V0. Further, the voltage VP applied across the load Z is 0. The compositions of voltage waves respectively traveling in the distributed constant lines 1xe2x88x921 and 1xe2x88x922 are represented by sums of a progressive wave and a backward wave as indicated at moment t=0 in FIGS. 18(a) and 18(b).
Namely, FIGS. 18(a) and 18(b) illustrate the conditions of the voltage waves respectively traveling in the distributed constant lines 1xe2x88x921 and 1xe2x88x922 upon completion of operating (namely, turning on)the shortcircuit switch S1 at the moment t=0 after received. To put it more precisely, these figures corresponding to the moment t=0 represent the conditions of these voltage waves immediately before the shortcircuit switch S1 is turned on. At a moment t=L/2 v, in the distributed constant lines 1xe2x88x922, the inversion of the polarity of the voltage wave occurs in a shortcircuit-switch-side part thereof, which is located at the side of the shortcircuit switch S1. In contrast, no variation in the voltage wave occurs in the distributed constant line 1xe2x88x921, because both of the shortcircuit-switch-side terminal part and the load-side terminal part thereof, which are respectively located at the side of the shortcircuit switch S1 and the side of the load Z, are open ends (to be exact, both of these terminal or end parts thereof are regarded as open ends because exchanges of energy actually occur between the load and each of the distributed constant lines 1xe2x88x921 and 1xe2x88x922 but the exchanged energies cancel out).
Subsequently, at a moment t=L/v, the load-side terminal part of the distributed constant lines lxe2x88x922, which is located at the side of the load Z, is put into a shortcircuited state, so that the voltage VP applied to the load Z becomes V0. This causes a variation in the voltage developed across the distributed constant line 1xe2x88x921. As described above, the impedance of the charger V0 is matched to that of the load Z, the voltage waves travelling in the distributed constant lines 1xe2x88x921 and 1xe2x88x922 are not reflected by the end surfaces thereof but start propagating therefrom to the load Z. Further, a voltage generated in a time period between the moments L=L/v and t=3 L/v is applied to and absorbed by the load, as illustrated in FIG. 18(c). As a result, the voltage, which has peak value (or potential) of V0 and further has a pulse width of 2 L/v, is supplied to the load Z, as illustrated in FIG. 18(c).
Thereafter, when the shortcircuit switch S1 is released or opened, the pulse generator is placed into the initial condition again. The process described hereinabove is performed repeatedly.
In the case that the peak (value of) voltage is raised by using the device illustrated in FIG. 17, a device configured as illustrated in FIG. 19 by stacking the devices, each of which is illustrated in FIG. 17, in such a way as to be independent of each other, suffices for such a purpose.
In FIG. 19, reference character V0 designates a D.C. charger; S1, S2, . . . , SN shortcircuit switches; 1xe2x88x921, 1xe2x88x922, 2xe2x88x921, 2xe2x88x922, . . . , Nxe2x88x921, Nxe2x88x922 distributed constant lines; L the length of each of the distributed constant lines; Z a load; VP an output voltage applied to the load Z; 3 a high-voltage-side wiring line; 4 a low-voltage-side wiring line; and 5xe2x88x921, 5xe2x88x922, 5xe2x88x92N short-circuit lines. Here, note that pairs of outer conductors ((1xe2x88x922b, 2xe2x88x921b), (2xe2x88x922b, 3xe2x88x921b), . . . , ((N-1)xe2x88x922b, Nxe2x88x921b)), each pair of which adjoin with each other as upper and lower stages, are connected with each other through connection lines 9xe2x88x921, 9xe2x88x922, . . . , 9xe2x88x92(N-1), serially, at the output-side terminal or end parts of the distributed constant lines 1xe2x88x921, 1xe2x88x922, 2xe2x88x921, 2xe2x88x922, . . . , Nxe2x88x921, Nxe2x88x922. On the other hand, the pairs of outer conductors ((1xe2x88x922b, 2xe2x88x921b), (2xe2x88x922b, 3xe2x88x921b), . . . , ((N-1)xe2x88x922b, Nxe2x88x921b)) are not connected with each other at the input-side terminal parts of the distributed constant lines 1xe2x88x921, 1xe2x88x922, 2xe2x88x921, 2xe2x88x922, . . . , Nxe2x88x921, Nxe2x88x922, which are located at the sides of the shortcircuit switches S1, S2, . . . , SN. A circuit illustrated in FIG. 20 is an equivalent circuit of the circuit illustrated in FIG. 19. In FIG. 20, same references numerals designate same components of the circuit of FIG. 19. Further, the (redundant) descriptions of such components are omitted herein.
Here, consider the case that all of the distributed constant lines 1xe2x88x921, lxe2x88x922, 2xe2x88x921, 2xe2x88x922, . . . , Nxe2x88x921 and Nxe2x88x922 from the bottom stage (namely, the first stage) to the top stage (namely, the Nth stage) as viewed in this figure, which have the same characteristic impedance and the same length, are used. Incidentally, in this case, it is assumed that the impedance of the load Z is matched to that of the power supply, namely, Z=Z1a+Z1b+Z2a+Z2b+ . . . +ZNa+ZNb.
In the initial condition, the shortcircuit switches S1, S2, . . . , SN are turned off. Moreover, the high-voltage side wiring line 3 indicated by the thick line is charged by means of the D.C. charger V0 to the voltage V0.
Upon completion of the charging, the shortcircuit switches S1, S2, . . . , SN are simultaneously turned on at the moment t=0. If the shortcircuit switches S1, S2, . . . , SN are completely simultaneously turned on, the voltage VP applied to the load Z at that time has the waveform as illustrated in FIG. 21. Therefore, a pulse, which has the peak voltage of NV0 and further has the pulse width of (2 L/v), is supplied to the load Z.
FIG. 17 is a diagram conceptually illustrating the configuration of another conventional pulse generator of the distributed constant type that uses parallel flat plates. In this figure, same reference characters designate same portions of FIG. 6.
As shown in FIG. 22, the distributed constant lines 11xe2x88x921 and 11xe2x88x922 have flat plates 11xe2x88x921a, 11xe2x88x922a and 11xe2x88x923, each of which has the same length L and further has the same width W. Further, the flat plate 11xe2x88x923 is inserted between the flat plates 11xe2x88x921a and 11xe2x88x922a in such a manner that these three flat plates are parallel to one another. At that time, the flat plate 11xe2x88x922 has the input-side terminal part connected to a terminal of the shortcircuit switches S1, which is opposite to the D.C. charger V0, and is grounded similarly as the flat plate 11xe2x88x921a that has the input-side terminal part connected to the low-voltage wiring line 4 serving as a grounding line. The flat plate 11xe2x88x923 has the input-side terminal part which is connected to a high-voltage-side wiring line 3. The flat plates 11xe2x88x921a, 11xe2x88x922a and 11xe2x88x923 are insulated by dielectric insulating materials (or insulators), which are inserted between the adjacent flat plates (11xe2x88x921a, 11xe2x88x923) and between the adjoining flat plates (11xe2x88x923, 11xe2x88x922a), respectively, and have the same dielectric constant ∈, the same magnetic permeability xcexc and the same thickness D and further have the functions similar to those of a capacitor.
Thus, the distributed constant line 11xe2x88x921, whose characteristic impedance is Z11a, is constituted by the flat plates 11xe2x88x921a and 11xe2x88x923, while the distributed constant line 11xe2x88x922, whose characteristic impedance is Z11b, is constituted by the flat plates 11xe2x88x921b and 11xe2x88x923.
The capacitance C (of these distributed constant lines 11xe2x88x921 and 11xe2x88x922) in this case is given by the following equation:
C=2∈LW/D. 
Thus, the capacitance C can be increased to a large value by changing the size (namely, the length Lxc3x97the width W), the thickness D or the dielectric constant ∈.
Here, note that the impedance of the D.C. charger V0 is matched to that of the load Z, namely, Z=Z11a+Z11b. Further, the distributed constant lines 11xe2x88x921 and 11xe2x88x922 have the same characteristic impedance. Namely, in the case of using the same distributed constant lines 11xe2x88x921 and 11xe2x88x922, the propagation velocities V of the voltage (wave) in these distributed lines are equal to each other.
Even in the case of the aforesaid pulse generator, which is thus configured by the parallel flat plates, the pulse voltage as illustrated in FIG. 18(c) is supplied to the load Z by the action similar to that in the case of the pulse generator configured by the coaxial cable of FIG. 5.
In the case that the peak voltage is raised by using the circuit illustrated in FIG. 22, a device configured as illustrated in FIG. 23 by stacking the circuits or units, each of which is illustrated in FIG. 22, in such a way as to be independent of each other, suffices for such a purpose. This device corresponds to the device illustrated in FIG. 19. Thus, in FIG. 23, same reference numerals designate same portions of FIG. 19. Further, the redundant description of such portions is omitted.
The pulse generator of FIG. 23 is obtained by stacking up N (stages) of the pulse generators, each of which has the structure shown in FIG. 22 and is used as a component unit. Namely, this device has the N stages of the distributed constant lines 11xe2x88x921, 11xe2x88x922, 12xe2x88x921, 12xe2x88x922, . . . , NNxe2x88x921, NNxe2x88x922, which are constituted by the parallel flat plates. Incidentally, in each pair (or stage) of the upper and lower stages, a single flat plate serves as both of the top flat plate of the lower stage and the bottom flat plate of the upper stage.
Even in the case of such a pulse generator, the pulse voltage illustrated in FIG. 21 is generated by simultaneously turning on the shortcircuit switches S1, S2, . . . , SN upon completion of predetermined preparation, similarly as in the case of the pulse generator of FIG. 19.
However, in the case of generating pulses be means of the pulse generators configured as illustrated in FIGS. 19 and 23, it is necessary to simultaneously turn on the shortcircuit switches S1, S2, . . . , SN, though the turning-on operation of each of these switches is not performed in exact timing (namely, in perfect synchronization) with those of the other switches and thus there is observed a phenomenon in which the output voltage VP drops. This is because of the facts that the pulse width is of the order of nanoseconds (ns) and is thus extremely short, that therefore, the influence of delay in the application of a trigger voltage or in discharge due to the difference among the wiring impedances respectively corresponding to the shortcircuit switches S1, S2, . . . , SN is enhanced and that it is difficult to time the operations of turning on the shortcircuit switches (namely, it is difficult to simultaneously turn on the N switches).
If there is caused the delay in the application of the trigger voltage, output voltages VP of three circuits have waveforms, for example, A, B and C as illustrated in FIG. 24. Thus, a synthesis pulse (A+B+C) synthesized from these three pulses A, B and C has a waveform as shown in this figure. Consequently, a pulse, which has an ideal waveform and has a pulse width of 100 ns and a peak voltage 3 V0, is not obtained.
The present invention is accomplished in view of the aforementioned various problems of the conventional apparatuses and methods.
Accordingly, a first object of the present invention is to provide a multi-stage exhaust gas treatment apparatus that can reduce the energy consumption of and decrease the size and weight of a gas treatment reactor which is supplied with energy from a high-voltage and has a reactor chamber for generating a streamer discharge plasma and decomposes toxic substances by letting exhaust gases flow through this chamber.
Further, a second object of the present invention is to provide a streamer discharge plasma gas treatment apparatus and method that save energy by preventing electricity (or power) consumption thereof from rising more than that in the case of employing the conventional chemical processing or treatment methods.
Moreover, a third object of the present invention is to provide a pulse generator which can supply outputs of a plurality of pulse generating portions, which are connected in parallel with one another, to a load as a pulse having an ideal waveform.
To achieve the foregoing first object, in accordance with an aspect of the present invention, there is provided an exhaust gas treatment apparatus configured by dividing a reactor chamber into a plurality of reactor sub-chambers and next connecting the plurality of reactor sub-chambers in series as a plurality of stages. Further, this apparatus is adapted so that large energy is cast into upstream reactor sub-chambers but energy to be cast into a reactor sub-chamber is gradually decreased as the reactor sub-chamber to be supplied with energy becomes closer to the most downstream reactor sub-chamber (less energy is supplied to each successive downstream-side chamber of the plurality of chambers). Incidentally, when connecting a plurality of reactor sub-chambers in series, a multiple stages of the reactor sub-chambers may be connected like a meander pattern or may be coaxially arranged.
With the configuration described herein-above, in accordance with the exhaust gas treatment reactor or apparatus and method, the waste of energy cast into downstream reactor sub-chambers can be minimized. In addition, the efficiency in the treatment of a toxic substance can be increased by setting the cast energy according to the concentration of the toxic substance at the inlet of each of the reactor sub-chambers.
Further, to achieve the foregoing second object of the present invention, there is provided a streamer discharge plasma exhaust gas treatment apparatus for detoxifying toxic ingredients or components contained in exhaust gases by using a streamer discharge plasma. In this apparatus, the (electron) density of electrons generated in a gas decomposition unit is set so that the electron density is high in a portion, which is located at a front or upstream side (namely, at the side of the upstream) of the exhaust gas flow, of the unit but is low in a portion, which is located at a back or rear side (namely, at a downstream side (that is, at the side of the downstream)) thereof, of the unit.
Moreover, the aforementioned streamer discharge plasma exhaust gas treatment apparatus is adapted so that the xe2x80x9cdensityxe2x80x9d of the number of turns (or what is called the wire density (namely, the number of turns per unit length)) of a coil for generating a streamer discharge plasma in the gas decomposition unit is high (or large) in a portion, which is located at an upstream side of the exhaust gas flow, of the unit but the wire density of the coil is low in a portion, which is located at a downstream side thereof, of the unit.
Furthermore, in the aforementioned streamer discharge plasma exhaust gas treatment apparatus, the flow velocity of the exhaust gas in the gas decomposition unit is set at a low value in the (front-side (or upstream-side)) portion, which is located at an upstream side of the exhaust gas flow, of the unit but the flow velocity thereof is set at a high value in the (rear-side or (downstream-side)) portion, which is located at a downstream side thereof, of the unit.
Besides, in accordance with a streamer discharge plasma exhaust gas treatment method, the toxic ingredients or components are detoxified by using one of the aforementioned streamer discharge plasma exhaust gas treatment apparatuses.
Incidentally, the xe2x80x9cstreamer discharge plasmaxe2x80x9d referred to herein is a discharge plasma in the initial condition of a discharge, in which a discharge path is formed. In this condition, high-energy electrons can be generated at an end of terminal portion of the discharge path. Therefore, the xe2x80x9cstreamer discharge plasmaxe2x80x9d is effective in treating exhaust gases.
Further, in the exhaust gas, the concentration of a toxic ingredient, namely, NOx or SOx is high in a portion, which is located at an upstream side of the exhaust gas flow (namely, at an inlet side), of the unit but the concentration of such a toxic ingredient is low in a portion, which is located at a downstream side thereof (namely, at an outlet side), of the unit. Furthermore, it has been known that because molecules of the toxic ingredient such as NOx or SOx are decomposed by high-energy electrodes generated by the streamer discharge plasma, a high-energy-electron generation rate in the downstream-side portion of the gas decomposition unit is lower than the high-energy-electron generation rate in the upstream-side portion thereof. Thus, in accordance with a technical idea of the present invention, the gas decomposition unit is adapted so that the high-energy-electron generation rate corresponds to (namely, is proportional to) the concentration (or the number of molecules) of NOx or SOx. Thereby, the excessive supply of energy is prevented, especially, in the downstream-side portion.
Note that the xe2x80x9celectron generation ratexe2x80x9d referred to herein is defined as the number of electrons generated per unit volume (or capacity) of the exhaust gas and per unit time, namely, the electron density (/cm3xe2x80xa2sec) of the exhaust gas. Thus, the present invention achieves the energy-saving by establishing the xe2x80x9cproportionality between the electron density (of an exhaust gas) and the concentration of a gas component to be decomposedxe2x80x9d. Additionally, in the description of the apparatus and method of the present invention, the expression xe2x80x9c(the electron density is set as being) high in the upstream-side portion, but is low in the downstream-side portionxe2x80x9d means in general that the electron density is set in such a manner as to decrease in the direction from the upstream-side of the exhaust gas flow to the downstream-side thereof.
Besides, to achieve the aforesaid third object of the present invention, pulse generators of the present invention employ the following configurations:
(1) A pulse generator of the present invention comprises:
a plurality of stages of a same configuration provided with distributed constant lines having high-voltage-side input-(side) terminal portions, which are connected in common to a high-voltage-side wiring line connected with a high-voltage-side terminal of a D.C. charger, and further having low-voltage-side input(-side) terminal portions, which are connected in common to a grounding line serving as a low-voltage-side wiring line connected with a low-voltage-side terminal of the D.C. charger,
low-voltage-side output(-side) terminal portions of the adjoining distributed constant lines, which respectively correspond to adjacent upper and lower ones of the stages, being connected in sequence or series;
a load connected between a low-voltage-side output(-side) terminal portion of a top one of the distributed constant lines of a top stage and a low-voltage-side output(-side) terminal portion of a bottom one of the distributed constant lines of a bottom stage; and
a shortcircuit switch connected between the high-voltage-side wiring line and the low-voltage-side wiring line.
(2) In the configuration (1) described herein-above, folded-back parts of core lines of the distributed constant lines respectively serving as component units of each single stage are connected to the high-voltage side wiring line. Further, two outer conductors surrounding remaining parts of the core lines, which are other than the parts connected to the high-voltage side wiring line, through insulating materials are connected to the low-voltage-side wiring line. Moreover, input(-side) terminal portions of adjacent ones of the outer conductors are shortcircuited by a shortcircuit line.
(3) In the configuration (1) described herein-above, two flat plates, each of which has a U-shaped section, of the distributed constant lines respectively serving as component units of each single stage are connected to the low-voltage side wiring line. Further, other two flat plates inserted between the two flat plates, each of which has the U-shaped section, through insulating materials are connected to the low-voltage side wiring line. Moreover, the flat plates connected to the low-voltage side wiring line are shortcircuited by a shortcircuit line at input(-side) terminal portions thereof. Furthermore, the flat plates connected to the high-voltage side wiring line are shortcircuited by a shortcircuit line at output(-side) terminal portions thereof.
(4) In the configuration (1) described herein-above, two flat plates, which are provided in such a way as to be parallel to each other, of the distributed constant lines respectively serving as component units of each single stage are connected to the low-voltage side wiring line. Further, another flat plate inserted between the two parallel flat plates in such a way as to be parallel with the latter two parallel flat plates is connected to the high-voltage side wiring line.